Body clocks and the science of sleep

ISOBEL DEANE (PODCAST HOST)

Welcome. This is the Sydney Ideas podcast, bringing your talks and conversations featuring the best and brightest minds at the University of Sydney and beyond.

FRAN KELLY

Sleep. I can't believe we've got a whole hour to talk about sleep. As a host of a breakfast radio program, for many years I actually never, never, never, never tired of talking about sleep because like many shiftworkers, it becomes an obsession in your life. I need more of it. How do I get more of it? How did I sleep last night? Will I sleep tonight? These are the questions that consume me, aand I think so many of us much of the time. Sad really, I know. But like many of you here, the search for a good night's sleep is a constant, constant quest, especially right now; I think for all of us who have been in and out of lockdowns during this pandemic.

I don't know about you. But prolonged lockdown has left me feeling more tired than ever, even as I am doing less actually than I normally would do in a single day. Some of us are finding it harder to get to sleep after a day in lockdown; and we know to the alarming impact that lockdown has had on people's mental health, particularly, but not only young people. So what's sleep got to do with it? Let's find out.

We know that getting enough sleep helps us stay healthy and alert in the short and the long term. But there are so many factors that can impact on our sleep and our sleep patterns, and that's what we're going to explore today.

What's the link between your sleep and your body clock and your bodies and your minds? How does the impact mood and depression? How does it impact diseases of the brain like dementia? And how do we get better at sleeping and sleeping well? How to get a good night's sleep?

Today our speakers will explain the science and the neuroscience of sleep, of our circadian rhythms; what happens during sleep and offer practical tips to to help all of us sleep a little bit at night or day depending on your job. Maybe you're a napper like me. Do naps work? That's the question I'm going to ask.

Now, let's meet our guests. Our first guest is Dr Jacob Crouse from the Brain and Mind Centre at the University of Sydney. Jacob is a postdoctoral research fellow with the Youth Mental Health and Technology team at the Brain and Mind Centre and recently part of a major research project on sleep, mental health and young people; it's just been published – the results – in The Lancet.

Professor Sharon Naismith from the Charles Perkins Centre at the University of Sydney is our second panellist. She's also part of that same research project Jacob was a part of it. Sharon is a clinical neuropsychologist. She's an NHMRC Dementia Leadership Fellow. She holds the Leonard P. Ullman Chair in Psychology at Charles Perkins Centre at Sydney Uni. She's also Head of the Healthy Brain Ageing Program at the Brain and Mind Centre, which is an early intervention research clinic for dementia.

And Associate Professor Sean Cain joins us from Monash University, hello Sean. Sean is an expert in circadian rhythms. He's the current president of the Australasian Chronobiology Society, where his lab focuses on individual differences in the sensitivity of the circadian systems, the light, and how these differences lead to poor health outcomes, including sleep disorders, metabolic disease and depression. So he's just the man to help you sort out your lights regime before you go to bed. He's already helped me with mine. He can he can be a great help. It's fantastic.

Alright, let's get cracking. Starting with the basics, what happens to us when we sleep? Sean? Talk circadian rhythms to us, what's the science of it?

SEAN CAIN

Well, most people don't realise this, but your bodies are made of clocks. We're actually made of trillions of clocks. We've got this bossy master clock at the base of our brain and it orchestrates the rhythms throughout the brain and bodies so you've got loads of clocks in your brain, loads of clocks through virtually every bit of tissue in your body, and they all want to keep a certain time. They want to do one thing at one time a day and other thing at another time of day. One of those one of those outputs is sleep. So it also tells you when to sleep, when to wake. But virtually everything going on physiologically, is timed by a clock.

FRAN KELLY

So just to stay with this for a moment, because I'm intrigued, lots of clocks? Not just one, sort of like a central nervous system clock – lots of clocks? Clock in your brain, clock in your stomach, tells you how to eat – that sort of thing?

SEAN CAIN

Absolutely, you've got a master clock at the base of your brain and the signals from your eye go directly to that area, and it serves as a sort of master clock. But you have other clocks throughout all the tissue of your brain. You've got clocks in your heart, clocks in your pancreas. Pretty much if it's tissue, it's rhythmic, and it's ultimately controlled by that central clock.

FRAN KELLY

So what happens to us when we sleep? What's happening to the clock?

SEAN CAIN

Well, the clock is always keeping time so when you're asleep, it is trying to maintain your sleep. In fact, at the latter half of the night, you get the strongest signals from your clock to stay asleep, so it keeps you awake during the day and it helps you maintain consolidated sleep in the night. But it's just trying to keep time.

For example, your heart, it's expecting to work hard during the day. But at night, it needs to recover from all of that work and so it tends to heal itself at night and work hard during the day; and the same can be said about all sorts of tissue in your body. Your body's not expecting to digest food in the middle of the night and so it's not really that prepared to do that.

FRAN KELLY

Sharon, does the same go for our brains? What happens to us when we sleep, what's happening to our brains? Because I know I sometimes feel like, I'm going to go to sleep and I have this belief that my brain will sort of data dump, clear itself up and sort itself out and it will think, she'll be right in the morning. What happens?

SHARON NAISMITH

Yeah that does kind of happen actually. There is a process where we clear our brains of waste when we sleep. But sleep actually occurs in 90 minute cycles roughly. So we do start off awake and then go into very, very light sleep and then gradually go into deeper stages of sleep, until we get into a really nice deep restorative sleep; so we call that slow wave sleep and that part of sleep is particularly important we think for restorative processes, for laying down new memories, for flushing the brain out of different toxins. And then we kind of cycle back up. And we might have a little bit of dreaming sleep, the rapid eye movement sleep, and then we'll do the cycles again through the night. So we go through a number of those processes.

When we start to dissect what's happening there, we will look more deeply at the sleep neurophysiology, we can see that the electrical activity in the brain actually changes a lot while we're sleeping and that coincides with those different sleep stages that we're in.

FRAN KELLY

Jacob, from your area of expertise. What happens to us in our sleep, what happens to our anxieties, our depressive moods, our moods; what's going on?

JACOB CROUSE

Yeah, that's a great question the Fran. I think that's been a concern for a long time. Shakespeare wrote that sleep was the most nourishing course in the feast of life and that sleep is important for healing wounded minds. I think a lot of us know this to be true. So like Sharon talked about, one of the major functions of sleep is restoration; so there's a clear up of the brain, this kind of housekeeping of metabolic waste that builds up throughout the day.

Sleep is also really key for the plasticity of our brain and some of these processes we know are involved in mental health conditions like depression and anxiety. A lot of these processes are really key and the frontal regions of our brain where we have these higher order cognitive processes that are engaged in anxious thinking and things like this; so sleep is really important for kind of rejuvenating these processes.

FRAN KELLY

We'll speak more more in depth about the brain and you know, depression and moods, those kind of things. But many of us here tuning in today are in lockdown; all of us on this panel are certainly in lockdown. So let's start off taking a look at the impact of this COVID pandemic and lockdown on our sleep.

Sean, anecdotally a lot of people are feeling more fatigued when they're stuck at home during lockdown. People are finding it harder to sleep. Is there a scientific reason for that? How is lockdown affecting our circadian rhythms?

SEAN CAIN

Just a spoiler alert. Pretty much everything I say is going to be that it's light. Light has a lot to do with it. We evolved with this bright sunlight; the sun comes up in the morning, same time pretty much every day. It falls; the sun sets and it's super regular. We've got bright days, dark nights.

But in our modern age, we're spending most of our time indoors. So it's really confusing for our clocks. We get actually quite bright nights. Now we have lights everywhere –overhead, LEDs, we have phones. Our lights are much brighter than they were traditionally. But also our days are less bright.

The clock really wants to know one thing – is it day or is it night? – and it gets that information from our environment. But 90% of our days spent indoors; never gets that bright light or very rarely gets the bright light it needs and it gets light that's too bright at night; and what this does is it dampens out those rhythms. So your body – all of these tissues of your body are less aware of what time of day it is. There's a sort of general confusion. We know that in depression, what's quite common is this lowering of the strength of the rhythm; it's also something that often happens in age. One thing that can really boost that is avoiding light at night and getting lots of bright light in the day.

FRAN KELLY

So why aren't we getting – I mean, we can make generalisations of course – but in lockdown, are you saying we're getting less natural light, because we're not leaving the house to catch the train to work or – but on the flip side of that many people might be going out for a walk in the morning because they've got the time to. Nevertheless, it seems almost universal – this my anecdotal experiment – that people are feeling more tired.

SEAN CAIN

Yeah. I think so, and I think this is part of it. So no-one likes commuting. But I think it actually served a good purpose, which is, you had to get up, and you had to get bright light at that same time every day so it's not just bright light in the day. Your body craves regularity. And the commute and the drive home; it was regular bright, light exposure. So we might be going out for a walk from time to time, probably not at regular times, probably not as much as we think we are, and so we're missing some light regularity, which causes us to just have these dampened rhythms and our clocks have a fair bit of confusion over that.

FRAN KELLY

Okay. Jacob, a lot of us are feeling more anxious or have been in and out of anxiety states during lockdown too for many obvious reasons. But is there a link between the growing anxieties brought about by the strangeness and sometimes the isolation of lockdown for people, or changing work patterns and our sleep? I know your centre has been looking at the impact of the pandemic on young people in particular. Well, can you shed some light on this?

JACOB CROUSE

Yeah, I think there's a lot to be anxious about at the moment. We're in one of the most uncertain times that most of us will have experienced and for young people, a lot of these concerns are economic. A lot of people aren't able to work and study as they were once able to; we're not able to interact with family and friends in ways that we're familiar with so there is this kind of growing stress response and anxiety. And I think this kind of constant concern about what's going on leads a lot of people to be thinking about these things before they're going to sleep, and kind of ruminating on them, which we know does lead to problems falling asleep. And I think coupled with some of what Sean was talking about, people are spending more time on their phones, and watching TV before bed. And we know that this does impacts the ability to fall asleep. So I think we have a perfect storm in a way for having poor sleep.

FRAN KELLY

Sharon, apparently a lot of people are reporting through lockdown that their dreams have changed as well. Have you heard of this? What are you seeing or concluding about the impact of the pandemic and lockdowns on sleep quality and patterns and dreams?

SHARON NAISMITH

I certainly have had heard a lot of people talking about their dreams. I do wonder if it comes back to you know Sean's point about circadian rhythms and that, because our dreaming sleep actually occurs during the later parts of the night. If we wake up in the morning, we actually wake up often when we're when we're dreaming and so I wonder if it's got something to do with that. I don't know of any research that has specifically looked at this phenomenon. But I do wonder whether it's just that we're waking more during that dreaming stage. So it's because of the timing of our sleep changing a little bit during the lockdown.

FRAN KELLY

You're a neuroscientist not a dream analyst. Let's stay with you for a moment and talk about sleep in our brains because a lot of the questions that have come in already are very, very kind of interested in in this. Particularly around the questions of sleep and dementia.

Belinda's asked, 'I read that there's a link between overuse of your brain that has never been able to turn off your thinking and dementia. Is that right? What are some settling techniques for turning off your brain? Because meditation doesn't work with busy brains.'

Now, for a start Sharon, is that known to be true – meditation doesn't work with dizzy brains? Have you got any advice here, or can you speak to this?

SHARON NAISMITH

Look, there's some evidence to show that meditation does work. I must say, there's not a huge amount of randomised control trials, which is the gold standard evidence that we'd be looking for that kind of thing.

There's certainly no evidence that I'm aware of that a busy brain in and of itself might lead to dementia. But a busy brain can also can lead to an inability to get to sleep because of anxiety, difficulty relaxing, and that kind of thing. So meditation may not be the answer for you.

I think the question is, what is the answer for the individual person to help them to get to sleep at night better, and to stay asleep and have that nice or deep quality sleep, and maybe we'll talk about that later when we talk about what you can do.

But certainly, I think finding those things prior to going to sleep at night like Sean's already alluded to – the lights are important. What's the thing for you that works in that light part of the night, and also, there's lots of things that can be done to help get that nice restorative sleep as well. So it's important to look at the big picture rather than just the one thing when looking at the sleep troubles.

FRAN KELLY

In terms of dementia, obviously dementia is a growing problem. Around the world, people talk about an epidemic, a global epidemic or pandemic that would be. Here in Australia, I think what the prediction's are is that we're gonna have a million people with dementia by 2050, I think is it?

SHARON NAISMITH

Right. Yeah, that's right.

FRAN KELLY

Which is enormous. Is there a clear link between dementia and poor sleep or lack of sleep? And does that mean that if you can get your sleep patterns going better now, you can stave off dementia. Is the link that clear?

SHARON NAISMITH

The link's not that clear. There was a big review of this – of all the risk factors for dementia. So we know that there are about 40% of dementia of the common types of dementia – Alzheimer's disease and vascular dementia in particular – about 40% of the risk for those is due to things that are modifiable. This could be cardiovascular disease, it could be depression, it could be low exercise, low education. Now, sleep was not included in that list of things that has a clear link, and I think that's because of the different methods that have been used in the field, so there's a little bit of uncertainty around that.

Having said that, there is very clear epidemiological evidence, so this is the evidence where we look at thousands and millions of people and combine that into one meta-analysis. So we bring all the studies together and we look at the evidence for that; and there is definitely evidence from those studies suggesting that sleep disturbance is linked with the later onset of dementia, so that comes from a few different areas. Some people report that their quality of sleep is not great and that's been linked to dementia. But more recently, there's been a lot of evidence looking at sleep duration – so sleeping less hours or less than six hours – there's a bit more of a robust evidence base behind that in particular at the moment, and potentially also, excessively long sleep seems to be linked with that.

And then the other big type of sleep disorder is sleep apnea, and there's a 26% increased risk of dementia for that. So I think that the reason why it's not clearly established as a risk factor is we're still really at the beginning stages of trying to unravel all of those precise elements of sleep, because sleep is not one thing. There are so many different things that sleep does in the brain and all of those hours are keeping to kind of keep our brains healthy.

FRAN KELLY

Yeah, I've read some of those reports, I must say, personally, as someone, because of my job doesn't get enough hours of sleep, I found it quite terrifying. Sean or Jacob, would you like to add to this?

Sean, I was wondering, someone's asked a question, for instance, 'Is the circadian rhythm a hormonal cascade and are there any other hormones that directly affect the circadian rhythm?'

In other words, if you were trying to correct your sleep, is there a hormonal answer to that; solution to that? Can you talk to that? And Jacob, do you have any views in terms of the link between the sleep and mind and a healthy mind and a mind that hopefully will stave off dementia or any any of those other diseases?

SEAN CAIN

I'll start off. It's a great question because every night, your body produces the sleep promoting hormone melatonin, so it's telling your body it's nighttime and you start to sort of relax and get a little bit sleepy. It occurs over several hours. One big problem is that our modern environments have so much light in them, that it actually suppresses that melatonin. We did a study in Australian homes and found that about half homes have enough light all the way up to bed to suppress about half of that melatonin so it's making it very hard to get sleepy to get to sleep; and in fact, it tricks your clock into thinking it's actually still daytime.

So if you're exposing yourself to too much light before bed, you're telling your clock, it's day, it's not night, it's actually not time to go to sleep. So it's no wonder people have trouble getting to sleep.

JACOB CROUSE

Again. Yeah, I might piggyback off what Sharon was talking about with some of these modifiable risk factors – so depression, being a really key one for dementia; and my team's major interest is in young people. So we know that most depressions will emerge when people are young, so in adolescence and early adulthood; and sleep does seem to be quite closely linked to certain kinds of depression.

There are certainly sleep disturbances observed in most people with depression. But we think that there's a causal element for certain individuals, so if we treat some of these sleep-like disturbances and some disturbances in the circadian cycle, we might be able to prevent some of this depression, and that might potentially have effects further down in life; so preventing some of the onset of dementia potentially.

FRAN KELLY

And can treating them be as simple as you know, Sean talked about melatonin? A lot of people take melatonin to regulate their sleep. I've never tried it. But does it work?

SEAN CAIN

There's good evidence that yes, that it does work. I think a lot of people will try melatonin and they expect it to be like a sleeping pill and it's not. It is sleep promoting, but it's not going to knock you out. So I think people's expectations tends to be a bit high for melatonin, and really, your body is producing it anyway. So if you just get the light right in your environment, your body produces its own melatonin, and that's probably the best place to start rather than getting exogenous you know, melatonin and a pill – just let your body do its work by keeping your environment before bed as dark as it can be for a couple of hours before bed at least.

FRAN KELLY

Jacob just back to something you said, they're pointing out that a lot of depression, anxiety; those kinds of disorders start in young people. Our sleep changes in our teens, too, doesn't it? Our actual sleep clock shifts? Have you been able to study or take a look at whether that shift is in kids who are coming into some kind of mental health disorder is linked somehow to that sleep circadian rhythm shift not happening as it should, or?

JACOB CROUSE

Yeah, that's a great question Fran. I think for whatever reason, society gives teenagers a really hard time about all kinds of things and their sleep is one of them. So we know that there is a biological shift during adolescence, where the kind of time of the circadian rhythm shifts so teenagers prefer to stay up later and wake later, and that's just a natural part of being a teenager. I don't know if work that has directly linked that to the onset of these problems. But we think that it's highly plausible that they are linked for certain people, whether there's something – yeah, there's kind of a mismatch in some of these issues, then it's kind of amplified as people get older.

FRAN KELLY

Let's stay with you for a moment in your study. While we're talking about depression, antidepressants, and even sleeping medications. Jacob, I think you've looked at the impact of anti-anxiety medications, antidepressants on young people; they didn't necessarily particularly help with them getting good night's sleep, did they?

JACOB CROUSE

Yeah, that's a great question. I think there are there are certain types of antidepressants. So for example, there's one antidepressant my team has studied called Agomelatine, which has antidepressant effects but it also seems to affect the circadian system; it affects the hormone melatonin. And there's some research that shows that drugs like that can help with some of these sleep-wake problems, which may underlie depression in some individuals.

So I think it's a bit of a tailoring of, what is the drug that we're using for a given individual and does it kind of map on to whatever problem may be underlying their issue? So it's a complex question and we've got a lot of work to do to really tease apart what is the right treatment for a given individual, and Sean's done some work; you might like to speak about it with antidepressants and light.

FRAN KELLY

Yes. Sean, I was just going to come to you before you go to light again. Is that it? You know, different people have different antidepressant medication, and anxiety medication works differently for different people. How do these medications work with our circadian rhythms? Is that important and is that so very individual?

SEAN CAIN

Incredibly important. So we're doing a study now funded by the NHMRC looking at the impact of selective serotonin re-uptake inhibitors on – surprise, surprise – your response to light.

So we did a study a couple of years ago showing that selective serotonin re-uptake inhibitors greatly increase the effect of light on the circadian system, and we think actually, that's why they work and why they don't work. So we think it's – it helps because there is an acute alerting and mood elevating effects of light. Light therapy is very useful, very beneficial for mood, and so we think that it's actually these drugs are boosting the mood elevating effects of light during the day. But also, they're making your circadian systems so sensitive to light, that a little bit of light at night can be very disruptive, so we think it's really a balance between the beneficial effects of boosting light sensitivity on mood during the day and the negative effects of having this potential disruption of light due to light at night.

So my advice would be stay regular, have bright days, dark nights, because it looks like these drugs might have a previously unknown side-effect of making you very sensitive to light disruption at night.

FRAN KELLY

So I have to ask, could all these problems be fixed with an eyepatch, you know, a sleeping mask?

SEAN CAIN

Well, if you've got light coming into your room at night, then definitely wear an eye mask. But no, my top tip is really, get some smart lights in your house, they're not too expensive. They'll keep you from having to remember to – 'Oh, it's eight o'clock, start turning the lights down.' When you set them up, set it and forget it. That's the way we evolved, we evolved to not control the sun, and to not have to think about it going up and down. So I would suggest that everyone just does this in their home, set it, it does its own thing, and you'll find that your sleep-wake cycle follows that light.

FRAN KELLY

Okay, before we finish that, I'm going to ask each of you for your top sleep tips, so you might remind us then at the end too Sean, about smart lights.

Sharon, what about sleeping pills, sleeping medications? We've talked about melatonin. But are these good for regulating sleep patterns in the short term and in the long term? Or can they get in the way of that?

SHARON NAISMITH

Yeah, look, most of the sleeping pills should only be used for short term use. Certainly in older people, the sleeping pills, particularly the benzodiazepines – so these are your Valiums, your Normisons – so those kinds of things should not be used. So the data shows that they create confusion, cognitive impairments – so problems of memory and thinking – and also falls in older people. So if they have to be used in the short term, you know, someone's grieving or there's some other kind of major event going on – that's okay, that's like a couple of weeks is okay. But beyond that they shouldn't be used, in older people.

Melatonin is better. There are some randomised control trials and meta analyses of melatonin in older people, even with cognitive impairment and even with Alzheimer's disease and actually shows that that is beneficial for sleep, and may even have more positive effects on cognition and mood. So that's definitely better than then using that. But also the gold standard treatment for sleep disorders is actually psychological and therapies which incorporate sleep hygiene; things you should do, practices that you should adapt, but also really working on the thinking around your sleeping as well. So there's lots of other things you can do besides pills.

FRAN KELLY

What do you mean by that Sharon, working on the thinking around your sleeping?

SHARON NAISMITH

Yeah, so there's a lot of data that suggests that our attitudes and our beliefs about sleep actually contribute and perpetuate our sleep problems. So I'm going to have a really bad night's sleep tonight and therefore you're kind of even when you wake up, you're kind of lying there thinking about how bad it is that you're lying there awake and actually contribute to not being able to get back to sleep.

Yeah and when you wake up, you actually – many people wake up from REM sleep, that dreaming sleep – and your brain is actually quite wired so it's like being in an awake state. And so you really need to give yourself 20 minutes also to just naturally fall back into that sleep stage. But a lot of people kind of obsess about that. So having a healthy understanding of sleep and an understanding that it does change a little bit as we get older is important and not to kind of dwell on it too much.

FRAN KELLY

Just the point about ageing. I'm just going to go to one or two questions that have been coming in. Someone else: 'I'm having trouble. I sometimes feel super tired when I go to bed. When when I get to bed, I wake up and I'm wide awake. I'm now aware this is the beginning of a night awake. This has been going on for many years now. I'm nearly 30. And I wonder if it's age related.' How much does age affect our sleep? More and more, you know, people that I know are waking up earlier, you know, and that's annoying to them. But they say, 'Oh, well, I'm getting older.' How much does age change the way you are?

SHARON NAISMITH

Well, I'll take that one first, because that's certainly Sean's area as well. But yeah, there is a natural advance of our circadian rhythm as we get older. Also, we do produce less of that hormone melatonin as we get older, so there's there's definitely evidence around that.

But in addition to that, there's changes in sleep, so we may sleep a little less than we used to. But also we have less of that really nice deep sleep as we get older. We have more awakenings during the night, and we have more light sleep, so we generally do tend to feel that our sleep is not as good quality as it used to be.

FRAN KELLY

And this goes to that feeling. Sometimes where you go to bed you sleep, but you still wake up tired. What explains that, Sharon?

SHARON NAISMITH

You do have to dig a bit deeper there because sometimes people can wake up tired because they've got other sleep conditions like sleep apnea, so that's kind of classic.

'I've had seven or eight hours sleep, I felt I was totally zonked out and had a great sleep, but I'm exhausted.' Are there other medications that are contributing to that? Sleeping pills are classic, you get that kind of hangover effects from that. And sleep apnea is another big one. So it's important in that respect to talk to your doctor to get down to the nitty gritty of why you're still waking up tired, despite a really good night's sleep.

FRAN KELLY

Okay, Sean, I see you nodding as you want to contribute to this.

SEAN CAIN

Sharon's really covered it. But yes, with age, you tend to see more of an advance of your rhythms, a dampening of rhythms have less of a signal for day and night. So perhaps less of a signal for alertness during the day and less of a signal for sleep at night, and part of that might be why you can wake out of sleep more easily, and perhaps not be able to get back into sleep. But Sharon also mentioned the lower melatonin, which is which is quite common. So you're not getting that signal that it's nighttime as readily.

FRAN KELLY

Does that mean we need less sleep as we age and therefore we should worry about not getting as many hours sleep or not?

SHARON NAISMITH

Yeah, look, I think the jury's still a little bit out on whether we need less sleep. Certainly as some of the data shows that maybe about an hour's less sleep is okay; and I think the key thing we have to remember here is that it's how you feel the next day that's important. So if you get less sleep, but you're still able to function well, then that's fine. You don't have any problem with your sleep,

FRAN KELLY

Jacob, this is an audience question too. 'As experts of sleep, do you feel it's hard to get to sleep yourself?' What's your experience?

JACOB CROUSE

Yeah, I've got a bad relationship with sleep myself. Sharon was talking about sleep apnea and that's something that I've dealt with for about 15 years now, which is maybe kind of some of the reason that I'm researching these kinds of things; to improve my own life.

But I think the last couple of years, I've really tried to protect my sleep at all costs. So kind of building walls around my sleep routines and, you know, trying as hard as I can to, yeah, have a good wind down routine and keep a regular schedule. But it is a challenge and especially during periods like this in lockdown, I think we need to also go easy on ourselves because there are a lot of factors at play.

FRAN KELLY

And we got heaps of audience questions coming in. So we will go to those in a second. But just a couple of quick ones. Sean, what about the impact on our physical health? Claudia wants to know – this was sent in earlier – 'Is there a connection between sleep deprivation and autoimmune disease? And if so, how is it connected?'

SEAN CAIN

In general for both rhythms and poor sleep, you'll tend to see more of a likelihood of getting ill, subpar responses to vaccinations and things like that, so it never goes the other way it seems. It's always you know, poor sleep and irregular timing of your rhythms – worse stuff.

FRAN KELLY

Okay. All right. What about this one, a quick one – alcohol. A lot of us think you know a bit of a drink at the end of the day is going to help us relax and now we get to sleep. True or false?

JACOB CROUSE

Alcohol does have sedative effects and it makes it easier to fall asleep but it also we know fragments our sleep or the the quality of sleep is actually poor. So yeah, it does lead to a lesser night's sleep.

SHARON NAISMITH

Just a little bit.

FRAN KELLY

Just a little bit? Okay not the bottle, just a glass.

SHARON NAISMITH

That's right. I don't know if anyone's ever experienced that – we have too much and you wake up in the middle of the night, which is that classic saying, you have a little bit, that's okay. It gets you off quite nicely. You know, nice and chilled.

FRAN KELLY

Okay, and this question from Lauren. I think it's a $64 million question really, given everything we've been talking about. Is it possible to reverse the effects of poor sleep habits, you know, four to five hours sleep per night? We saw on the poll that some of us get that little. Is five hours too little; and can you reverse the impact on it?

SHARON NAISMITH

Look, I don't know of any studies that have shown that you can reverse the effects of sleep deprivation. We only know of studies studies. But what I would encourage people to do is certainly to try and catch up on the weekend, I saw some other things in there about four hours sleep and external stressors. I mean, there is strong data now on this, you know, only four hours sleep. I would be addressing the external stressors, and I would say prioritise sleep. Don't prioritise, you know to the extent that you can – if it's work and other things – try to minimise those or change them in your life. Because the short sleep for four hours is not great. Unless that's naturally you, unless you've always been.

FRAN KELLY

And Sean, that notion of catching up on the weekend, does that work? Can you sort of kick around your circadian rhythms like that?

SEAN CAIN

Well, it's a bit of a problem. Because if you are catching up, you're having a different kind of light exposure and sleep wake pattern during the week versus the weekend, something that we call social jetlag; so your signals to your clock of day and night are getting messed up and moved around. If you try to keep very regular, that's the best you can do.

In fact, I tell people don't stress out too much about going to bed and just having to sleep. Get the the light right, and your body will follow. So keep your home dim and at night, as much as possible, you will eventually probably fall asleep naturally. So just try it out for a week. Try not having these bright overhead LED lights, try not using your phone at night, just for a week, and you'll see that your your your body takes over it does what it wants to do.

FRAN KELLY

I have this image of you Sean, creeping around a very dark house at night. Let's take some of the audience questions now. See what Slido's got to show us. Top question. This one's for you very directly, Sean I think. 'Is there a way to find out the natural circadian rhythm of a person? Is there such a thing as night owls and early birds?' Sean, we'll start with you, and then Jacob, I think you've got stuff to say on this too.

SEAN CAIN

Yeah, so we all have slightly different rhythms and there are people who tend to be night owls, tend to be early birds. The interesting thing is it's partly artificially created by our light exposure patterns in our individual differences of light sensitivity. If you bring someone out camping – a night owl and an early bird out camping – they'll tend to have the same rhythms and the same sleep-wake cycles. So you have strong input. So bright days, dark nights. We're all kind of the same. But in these artificial lights, differences in sensitivity and differences in timing of our behaviour, it pushes some people apart. It is true, there's something within us that will tend to push us one way or the other. But if you get very, very bright days and very dark nights, we all tend to keep quite similar timing.

FRAN KELLY

And Jacob this notion that some people are night people, some people are morning people. Yet, you know, you might be morning people, but you get squished into a nine to five kind of cycle, which is how most people work. Have you have you had a look at this?

JACOB CROUSE

I haven't personally but there is a lot of data on this. So there are genetic factors that kind of push us one way or the other way and people that have some of these genetic variants that are associated with being a night owl seems to be more at risk for having mental health problems. And like I was talking about how we don't treat teenagers very well, in society we also don't treat night owls very well. So our society is a nine to five society so I think there does need to be more flexibility for people that are potentially pushed towards that direction around how they spend their time in a way that potentially best suits their biology.

FRAN KELLY

Yeah, this is another question, very popular. Has the blue light myth been busted yet?

SEAN CAIN

I'd like to take this. There are some very wrong ideas about about blue light. So blue light is not bad.

FRAN KELLY

What is it? What is blue light?

SEAN CAIN

Well mobile phones tend to have a lot of blue light but overhead LED lights, they tend to have a lot of blue in them that might look white. But you know, if you measure the wavelength of light, they're quite enriched in blue, and it's not – blue light isn't inherently bad.

The photoreceptors in the eye that feed into the clock are most sensitive to blue light, and they want as much light as you give them, as much blue light as you can give them in the day but very little at night because they're so sensitive to blue light, it doesn't take much to activate them. In fact, once these particular photoreceptors are activated, they can stay activated for a long time for several minutes. So when you close your eyes at night, if you were exposed to a lot of blue light, you're seeing nothing but unconsciously, there are signals from these blue light receptors to your brain saying, 'Hey, you're looking at light, it's actually still daytime.'

FRAN KELLY

Okay, so it's not a myth?

SEAN CAIN

It's a myth that it's bad for you in the day, so you shouldn't be wearing any kind of glasses that block blue light during the day – that's silly. You want as much blue light as you can get in the day and as little at night. So it all depends on time of day. So there's not a blue light myth really, but just it's a little more subtle than that.

FRAN KELLY

Okay. What about this question on screen about menapause? It's well known that menopause can really disturb people's sleep. Someone says, 'I was a peaceful sleeper, but now wake up all the time. As both my parents had dementia, I think good sleep is essential. Any tips to restore sleep pattern post-menopause?' Sharon, do you want to start first with this? And then it Sean or Jacob, you got anything to add?

SHARON NAISMITH

Yeah, so I mean, menopause is associated with changes in the – getting to sleep can result in awakenings, can result in early morning awakenings, and can also result in lots of awakenings during the night.

There are other things that happen with menopause and other medical conditions that can contribute to those sleep problems. So that's key, looking at those and how that may be contributing as well.

The other thing is depression and anxiety may peak at this time as well so certainly, addressing those. Depression and anxiety are some of the biggest causes of sleep problems so that's usually critical, even if it's very mild depressive symptoms, to really have a good look at that.

The other thing that I would say is it's important to think about the lifestyle approaches so staying physically active, cognitively active is really important, but also even consider, you know, trialling cognitive behaviour therapy – so four sessions of cognitive behavioural therapy for insomnia can actually be really helpful either with a psychologist or it actually you can even do it online now.

There are a couple of online programs, one is called Sleepio, and other one's called Shuteye, and they have really good evidence base around them. They're personalised to you, someone kind of walks through the different options with you, so even if you're not in a big city, or you can't afford to go to a psychologist, or any of those kinds of things, there are options to tackle your sleep in that way.

And the other thing I would say is, maybe talk to your doctor about trialling melatonin, that may well be worth considering as well.

FRAN KELLY

We're going to run out of time soon, and I want to get your tips before we go, so let's crack on here. What about this question, because I'm interested in this; 'Do we have to sleep eight hours all at once? Could it be broken? For instance, into four two-hour breaks?' I think I know the answer to that. But it brings into my sort of obsession about napping, does it work and does it all count together towards a good night's sleep?

SHARON NAISMITH

Look, it's really important to get the deep sleep, the slow wave sleep, that often happens first. So we we usually go into that nice deep sleep. I don't believe that it should be broken up into four chunks because sleep consolidation and the continuity of sleep is very important. It's obviously very rhythmic. As you know, Sean has kind of alluded to, we flow in and out of these cycles, they relate to each other. I wouldn't be breaking it up.

I guess if you're desperate, and you have to do it that way, it's still better to get that sleep, and we we don't know enough yet about whether the brain will ensure we get all the critical amount if it's broken up like that. But my hunch would be try and get it in one shot.

FRAN KELLY

Yeah, and if I could add, your body's expecting to sleep at some times of day and not at others so any sleep that you try to get during the day, it's not going to be your best sleep. You're getting signals for alertness at that time. Now, you might nap because you're exhausted and you're getting bad sleep at night and so that sleep pressure overwhelms the signals for wakefulness. It's not so great but it's necessary and if you're doing shift work or things like that.

Okay, what about, 'Can of waking up at the same time in the middle of the night reset your clock, so that becomes a pattern that's hard to break?' Sean?

SEAN CAIN

That is a brilliant question. Yes, it tends to be able to get set up in a sort of rhythm in arousal. I would suggest that people, if they do wake up, at least don't turn on the lights, giving the signal that actually now it's dawn and your clock will move toward it. But yeah, it can set itself up as a rhythm so it's unfortunate but it does happen. Happens to me quite a bit.

FRAN KELLY

Jacob, I'm going to try and bring you in the dreams I don't know if you know about it, but do vivid dreams you recall in the morning influence your quality of sleep, or I would add, say anything about the quality of your sleep?

JACOB CROUSE

Yeah, I'm not actually too sure about dreaming. I know, like Sharon was speaking about before. When people are waking up during REM sleep, they might be more likely to remember dreams being vivid, but I'm not sure about the quality of sleep. Sharon might like to talk about that.

SHARON NAISMITH

No, I don't add anything there. I think the quality, you have to think about how much of that deep restorative sleep you're getting. I don't know that we know anything about the vivid dreams and the quality of sleep.

FRAN KELLY

And what about coffee? Can any of you shed any light on coffee? We've talked about alcohol, but does one coffee before midday really affect your sleep? How much would it affect the natural rhythm if you had a coffee once a day in the morning, or as some people I know, have five coffees in the morning, they seem to sleep okay at night. Other people, one coffee after lunchtime does them in.

SHARON NAISMITH

I'd say you've hit the nail on the head, it comes down to the individual. I used to be able to have coffee all day long and now I have to stop it like, before three o'clock. Otherwise, it impacts on my sleep; ability to get to sleep. So I think that you have to remember that your sensitivity to caffeine changes as you get older as well. And you need to, if you're finding it's impacting on your sleep, just cut it out. Sean, you might have thoughts about circadian rhythm and caffeine?

SEAN CAIN

Well, yeah, I could talk about the fact that caffeine interacts with light as well and so any effects of light are going to be enhanced, which you know, might be good in the day; you get you get that extra boost in the effect of light. But it also has such a long half-life that if you have it even into the afternoon, there's still plenty in your body when you're trying to get to bed, so perhaps that light from your phone is having a much bigger effect than it would.

FRAN KELLY

Let's I think start to wind up now. You're all experts in your own areas. You've all got something to offer I think, so before we go let's give everyone a take-home gift. Can I get a final tip from each of you. Jacob, we'll start with you. Your best tip – we've all heard that you don't sleep very well so this might be a problem for us – but from all the research, your best tip for our sleep hygiene?

JACOB CROUSE

Yeah I think, thinking about sleep and wake being two sides of the same coin – so really keeping in mind that how we spend our days influences our night, and how we spend our night influences our day. We have a lot of control over how we spend our day. I think bringing together some of these things that we know are associated with good mental health so being physically active, socialising with people and getting exposure to light during the daytime and trying to do all these things at the same time could have a really positive effect on how we sleep and the rhythmicity of our circadian rhythm.

FRAN KELLY

Just a little more on that physical health thing. I've always wondered – we're always told go out and get some; do some physical exercise. Is that to physically make our bodies tired? Or is it something else we're getting when we're out exercising?

JACOB CROUSE

I mean, exercise does give us endorphins and it relates to different factors that are associated with brain health, and it does help us fall asleep easier and seem to have a better night's sleep.

FRAN KELLY

Sean, your best tip? We know it's about light.

SEAN CAIN

Yeah, two quick tips. One is a simple one. Get smart lights. If you have to remember to turn your lights down at night, you're going to forget a lot of the time. Your light cycle is going to be irregular. Set them up on timers, go to Bunnings, JB Hi-Fi; they're not that expensive.

FRAN KELLY

Just to stop you there Sean, because when you say get a smart light, I didn't know what you meant. Do you just mean, you get a timer. How do you attach your timer to your bed lamp? Is that what you're talking about?

SEAN CAIN

Yeah, smart lights, they can change in their hue so that they can be more bright white and blue. That's fine during the day, you want them as bright and blue as possible. But they can also change to more of an orange kind of candlelight colour and you can make them go very, very dim.

If you just set them up to be dim and orange at night and bright and white in the day at the times you want to be awake and go to sleep – you'll never have to think of it again.

FRAN KELLY

Okay, that's tip number one. What was tip number two?

SEAN CAIN

So tip number two is easy. If the sun is out, go and get some light. If the sun is not out, avoid light.

FRAN KELLY

You don't want to go outside if the sun's not shining?

SEAN CAIN

Yeah, well. Your circadian clock, it doesn't really know the difference between it being overcast, or very, very bright. There's enough light out there to do the trick, even when it looks a little grim and dim.

FRAN KELLY

Get out there.

Sharon, your best tip.

SHARON NAISMITH

Yeah look, I've got two very different ones. One, particularly as it relates to older people, and when I say that I say actually anyone over the age of 40 because that's when all the pathology that leads to dementia starts to build up in our brain, so from that age, really we should be looking out for things that we can do to prioritise sleep. One big one is sleep apnea – so snoring, daytime sleepiness – look out for those. Go talk to your doctor, there are a gold standard treatments for it. We know that sleep apnea starves the brain of oxygen, it fragments our sleep a lot, it can be treated, so look out for that one.

FRAN KELLY

So take it seriously, get some advice and get some help.

SHARON NAISMITH

Even mild sleep apnea – so having five of these events an hour, that's actually when you stop breathing during sleeping, so you kind of gasp for air because of obstruction of the airway – it's actually fairly significant.

The other one, I think, is really just touching on what Jake said, as well, prioritising sleep is important, but we want to make sure we're getting that really nice deep quality sleep. So physical activity, resistance training and aerobic activity have both been shown to improve our slow wave sleep – so how deep we go into that state – that's when our brain is clearing all the toxins out in that nice deep, slow wave sleep.

But the other thing is cognitive activity so just because we get older doesn't mean we have to keep doing the same thing. Keep the brain active, learn new skills, learn new languages, change your job, get more complexity in it, and stay socially connected. All of those things are important for keeping our brain active.

FRAN KELLY

Just to drill down into the cognitive activity, that doesn't just mean doing crosswords and doing Sudoku, it means changing it around. Is that right? So you can't just read novel after novel after novel?

SHARON NAISMITH

Our brain gets lazy. We want to challenge it for new optimal neuroplasticity. We want to give it new things, get different neurons talking to each other so keeping it challenging and mixing it up a bit.

FRAN KELLY

It is hard work. We can just never take our foot off the pedal, can we? I'm going to go to you on this one, Jacob. Someone's just written in, squeezed it in, 'There's been studies into music and how it affects our sleep.' What are your insights into this Jacob? I don't know if you have an insight into this, but let me ask you anyway.

JACOB CROUSE

Unfortunately, I don't know. You know, listening to music before we go to sleep can be part of our routine.

FRAN KELLY

You're someone who's had trouble with sleep, have you tried music, has it helped?

JACOB CROUSE

I haven't tried it, I have used that as a bit of a calming kind of technique. But nothing beyond that. Sharon?

SHARON NAISMITH

We do know that there are studies that use acoustic stimulation so noises that are linked to pick up our – it's a technology that's not available yet. But that actually does enhance our slow wave sleep and some of the neurophysiology. So some work – people in Sean's group, Clare Anderson – is looking at that, and so there's probably something in the music that may well prove to be important, but we're not quite there yet with the science.

FRAN KELLY

There's always something in the music.

That's it from us for today. I want to thank you all, thank you for your tips. These will all be collated and all this advice and the references of our panellists will be there on the Sydney Ideas website attached to this.

But you know, you can write it down now. Get your smart lights, it's all about your lighting. If you don't have a smart light, I think you just need an eye mask perhaps, to do a lot of what Sean was telling us.

Get your physical exercise, get out into the daylight when you can, make sure you do it every single day. We know all this, we are told all this. It's good for our hearts. It's good for our minds. It's good for our sleep. So get physical exercise. Get your lighting right.

And if you are a snorer, if you've got any kind of sleep issues, Sharon says go to the doctor sooner rather than later.

Thank you very much, Sean Cain, Jacob Crouse and Sharon Naismith, you've been fabulous, thank you very, very much.

And something really fabulous apart from the tips from the experts today for you to take away into your daily life. We're putting together a Spotify playlist for you, how good is that? So talking about music, think of it as music to relax by, which includes a random selections from our panellists, so the experts scientists have given you the great musical tips here. Jacob was keeping that from you but he's contributed too. I put a touch of Gurrumul on there as my contribution because he does it for me every single time. Some of the people joining in too, have given us ideas; so it's a terrific playlist, head to Spotify, Sydney Ideas, it'll be there, and we'll add that to the website too if you can't find it.

I'm Fran Kelly. This has been a Sydney Ideas event for the University of Sydney. It's been absolutely fantastic. It's been a thrill to be here. So thank you for joining us, and I hope you can join us again. Have a great day. Have a great evening, and best of all, have a great sleep.

ISOBEL DEANE (PODCAST HOST)

Thanks for listening to the Sydney Ideas podcast. For more links, resources or the transcript, head to the Sydney Ideas website or subscribe to Sydney Ideas using your favourite podcast app.

Podcast transcript

Research by the panel

Mental health and support

Dr Jacob Crouse, Brain and Mind Centre, University of Sydney

Associate Professor Sean Cain, Monash University

Professor Sharon Naismith, Charles Perkins Centre, University of Sydney

Fran Kelly, ABC Broadcaster (Moderator)

Body clocks and the science of sleep

Watch on-demand

Catch up on podcast

Resources

Podcast transcript

Research by the panel

Mental health and support

The panel

Dr Jacob Crouse, Brain and Mind Centre, University of Sydney

Associate Professor Sean Cain, Monash University

Professor Sharon Naismith, Charles Perkins Centre, University of Sydney

Fran Kelly, ABC Broadcaster (Moderator)

Catch up on podcast

Learn more about our research

Check out our playlist: Songs to wind down to